What is oversteer exactly?

Let's say you're driving home, on a street you use every day, and it's raining. You make a turn which you've made hundreds of times before, but instead of the car turning 90 degrees at the intersection with your typical amount of steering wheel input, it actually turns more than that - it may even feel like the back end is sliding around the turn faster than the front end - <p>That's oversteer. <p>For a given amount of steering input, the car turns more.<p><br>Tor Quemada